Error on the ratio between N(HDCO) and N(H₂CO) (left panel), N(D₂CO) and N(H₂CO) (middle panel), and N(D₂CO) and N(HDCO) (right panel). The black contours represent increasing 10% steps of the peak of the Herschel N(H₂) map, presented by Spezzano et al. (2016). The beams are shown in the bottom right corner of the figures, in yellow for Herschel/SPIRE and in white for the 30 m telescope. The black cross marks the dust continuum peak.